The invention relates to couplings enabling a drive shaft to be connected to a driven shaft, such as in particular a rod having an end of noncircular section and a fork of U-shaped section, and has more particularly as its subject a coupling device of this kind which can be placed in position quickly and is also reliable both during this operation and during its functioning.
In numerous technical fields it is necessary to couple two shafts, for example a rod to a member such as a fork, said rod and said fork each being associated with one of the shafts, in such a manner as to connect the latter together for co-rotation.
This type of situation is for example encountered in the automobile industry when it is required to connect the rod of a steering gearbox pinion to the jaw of a universal joint fastened to one of the shafts of a steering column.
One technique in use at the present time consists in arranging for the fork associated with the shaft, which is to be fastened to the pinion end of noncircular section, to be connected to one of the jaws of the universal joint in such a manner as to be pivotable about one of the cross pins of the universal joint, and for said fork to engage over the end of noncircular section of the pinion when it is turned down onto said end by pivoting. The end of noncircular section, which is then held captive in the fork without being able to turn, is immobilized with the aid of locking means.
These locking means usually consist of a threaded rod which is provided with cams on its periphery and which is passed through the fork and then clamped on the latter with the aid of a nut. The rod is turned so that the cams on its periphery drive the end of noncircular section towards the bottom of the fork, whereupon the end is clamped by screwing the nut onto the threaded rod portion which projects out of the fork. If use is made of a nut equipped with a braking device, after several turns of the nut the rod will come into contact with the braking or locking device and the torque is increased; when the nut is turned further, it drives the rod rotationally in its movement and one of the cams of the rod comes into contact with the end, which it then drives towards the bottom of the fork; additional screwing then effects the locking.
Although a technique of this kind is in general satisfactory, it is far from being free of disadvantages during assembly.
Moreover, if the locking means should slacken and become free from the fork during operation, the fork may become detached and the two shafts originally coupled together will no longer be connected to one another. It will readily be understood that this insidious situation is particularly troublesome in the case of a motor vehicle steering system.
Assembly work of this kind is generally done in the engine compartment of a vehicle, where space is particularly scarce. In order to place the rod and the nut in position the operator must use both his hands at the same time. This is particularly difficult if it is recalled that, in addition to the restricted free space available to the operator, access to that space is very often inconvenient; this considerably hampers the placing in position and the utilization of automatic screwing equipment of the compressed air or electric motor type.
The invention seeks to obviate the shortcomings of the known technique, particularly those briefly mentioned above, by ensuring that the device proposed can be rapidly and reliably assembled and can be placed in position easily.